Mark an unreachable case as a bug instead of attempting to show an error to the user

oli-obk · oli-obk · commit 4fba7d33d614 · 2018-07-23T09:51:30.000+02:00
diff --git a/src/librustc_mir/borrow_check/mod.rs b/src/librustc_mir/borrow_check/mod.rs
@@ -1853,7 +1853,7 @@ impl<'cx, 'gcx, 'tcx> MirBorrowckCtxt<'cx, 'gcx, 'tcx> {
                 }
             }
             // promoteds may never be mutated
-            Place::Promoted(_) => Err(place),
+            Place::Promoted(_) => bug!("encountered mutable promoted"),
             Place::Static(ref static_) => {
                 if self.tcx.is_static(static_.def_id) != Some(hir::Mutability::MutMutable) {
                     Err(place)

Original file line number	Diff line number	Diff line change
`@@ -1853,7 +1853,7 @@ impl<'cx, 'gcx, 'tcx> MirBorrowckCtxt<'cx, 'gcx, 'tcx> {`
`1853`	`1853`	`}`
`1854`	`1854`	`}`
`1855`	`1855`	`// promoteds may never be mutated`
`1856`		`- Place::Promoted(_) => Err(place),`
	`1856`	`+ Place::Promoted(_) => bug!("encountered mutable promoted"),`
`1857`	`1857`	`Place::Static(ref static_) => {`
`1858`	`1858`	`if self.tcx.is_static(static_.def_id) != Some(hir::Mutability::MutMutable) {`
`1859`	`1859`	`Err(place)`